Steam Inlet Valve of a Steam Turbine

Abstract

A steam inlet valve ( 1 ) of a steam turbine, with a valve seat ( 2 ) and a valve body ( 3 ) which, when the valve is closed, bears via a contact region ( 5 ) with sealing effect on a contact region ( 5′ ) of the valve seat ( 2 ). At least one of the two contact regions ( 5, 5′ ) has at least one sealing region ( 6 ) which faces the other contact region ( 5, 5′ ), a base region ( 7 ) which faces away from the sealing region ( 6 ), and a transition region ( 8 ) which is situated between them, wherein the sealing region ( 6 ) is formed from a sealing material (B) and the base region ( 7 ) is formed from a base material (A), which the valve seat ( 2 ) or the valve body ( 3 ) also approximately comprises. In order to increase the wear resistance of the contact regions ( 5, 5′ ) and of the steam inlet valve ( 1 ) as a result of it, the concentration of the base material (A) reduces from the base region ( 7 ) in the direction towards the sealing region ( 6 ) in the same way as the concentration of the sealing material (B) reduces from the sealing region ( 6 ) in the direction towards the base region ( 7 ), so that both materials (A, B) are to be found in the transition region ( 8 ).

1 . A steam inlet valve of a steam turbine, the inlet valve comprising:
 a valve seat having a contact region; and   a valve body having a contact region;   wherein, when the valve is closed, the valve body contact region sealing bears on the valve seat contact region;   wherein at least one of the contact regions has at least one sealing region which faces the other contact region, a base region which faces away from the sealing region, and a transition region situated between the sealing region and the base region;   wherein the sealing region is formed from a sealing material and the base region is formed from a base material, the valve seat or the valve body comprising the base material; and   wherein the concentration of the base material reduces from the base region in the direction towards the sealing region, and the concentration of the sealing material reduces from the sealing region in the direction towards the base region, so that the transition region comprises both the base and sealing materials.   
   
   
       2 . The steam inlet valve as claimed in  claim 1 , wherein the sealing region is produced as a separate component and is bonded to the base region via the transition region. 
   
   
       3 . The steam inlet valve as claimed in  claim 1 , wherein at least one of the sealing region and the base region is produced together with the transition region. 
   
   
       4 . The steam inlet valve as claimed in  claim 1 , wherein at least one of the sealing region and the base region is welded to the transition region. 
   
   
       5 . The steam inlet valve as claimed in  claim 1 , wherein:
 the transition region and the base region are sintered or hot isostatically pressed; or   the transition region and the sealing region are sintered or hot isostatically pressed; or   the transition region, the base region, and the sealing region are sintered or hot isostatically pressed; or   the base region and the sealing region are sintered or hot isostatically pressed.   
   
   
       6 . The steam inlet valve as claimed in  claim 1 , wherein the sealing material comprises at least one element selected from the group consisting of chrome, tungsten, nickel, carbon, cobalt, and molybdenum. 
   
   
       7 . The steam inlet valve as claimed in  claim 1 , wherein the sealing region comprises or is formed by a stellite alloy. 
   
   
       8 . The steam inlet valve as claimed in  claim 1 , wherein the base material is cast steel, forged steel, or a nickel alloy. 
   
   
       9 . The steam inlet valve as claimed in  claim 1 , further comprising:
 at least one transition material which is different from the base material and from the sealing material, the at least one transition material located in the transition region; and   wherein the concentration of the transition material reduces from the transition region towards the sealing region, towards the base region, or towards both; or   wherein the concentration of the sealing material reduces from the sealing region towards the transition region; or   wherein the concentration of the base material reduces from the base region towards the transition region.   
   
   
       10 . The steam inlet valve as claimed in  claim 9 , where at least one of the base material and the sealing material has a concentration minimum at a point of a concentration maximum of the transition material. 
   
   
       11 . The steam inlet valve as claimed in  claim 1 , wherein at least one of the base material, the sealing material, and the transition material is formed at least partially from metal powder.